Power assist steering apparatus and method responsive to volume flow of fluid

Abstract

An apparatus and method for providing power assisted steering for a marine craft having a manually operable steering pump and a hydraulic steering actuator. A powered hydraulic pump is hydraulically connected between the manually operable pump and the actuator. Hydraulic fluid volume output of the steering pump and hydraulic fluid volume output of the powered pump are sensed. The fluid output of the steering pump is compared with the fluid output of the powered pump and the powered pump is operated so that the output of the powered pump is commensurate with output of the steering pump.

1. A power assist apparatus for a hydraulic steering system, comprising:
 a directional control valve; a first valve port hydraulically connected to the control valve and being connectable to a first pump port of a manually operable steering pump; a second valve port hydraulically connected to the control valve and being connectable to a second pump port of the manually operable steering pump; a third valve port, a fourth valve port, a fifth valve port and a sixth valve port; a powered hydraulic pump having an input port and an output port, the input port and the output port being hydraulically connected to third and fourth ports of the control valve, respectively, the control valve having a member displaced in a first manner when hydraulic fluid flows into the apparatus through the first valve port, said member being displaced in a second manner when hydraulic fluid flows into the apparatus through the second valve port; a position sensor for detecting movement of the member; a controller for operating the powered hydraulic pump, said controller receiving signals from the sensor to operate the pump when hydraulic fluid flows into the apparatus through the first the valve port or the second valve port, the fifth and sixth valve ports being for hydraulic connection to a steering actuator, the control valve connecting the output port of the pump to the fifth valve port when hydraulic fluid flows into the apparatus through the first port and connecting the output port of the pump to the sixth valve port when hydraulic fluid flows into the apparatus through the second port. 
 
     
     
       2. The apparatus as claimed in  claim 1 , wherein the control valve is a spool valve and the member is a spool thereof. 
     
     
       3. The apparatus as claimed in  claim 2 , wherein the control valve is a 3 position, 6-way valve. 
     
     
       4. The apparatus as claimed in  claim 1 , wherein the pump has a variable speed motor, the controller being a proportional controller, whereby speed of the motor is proportional to displacement of the member of the control valve. 
     
     
       5. A power assist steering apparatus, comprising:
 a powered hydraulic pump; a first port for receiving hydraulic fluid from a manually operable steering pump; means for detecting a flow of fluid into the apparatus through the first port; a controller for operating the powered hydraulic pump when said flow of fluid into the apparatus through the first port is detected; a second port for outputting fluid to a hydraulic steering actuator; and means for directing hydraulic fluid output from the powered hydraulic pump to the second port, and for directing fluid flowing into the apparatus to the powered hydraulic pump, when said flow of fluid into the apparatus through the first port is detected. 
 
     
     
       6. The apparatus as claimed in  claim 5 , wherein the means for detecting includes a member movable by fluid flowing into the apparatus through the first port and a position sensor adjacent thereto. 
     
     
       7. The apparatus as claimed in  claim 6 , wherein the means for directing including a control valve, the member being a spool of the control valve. 
     
     
       8. The apparatus as claimed in  claim 7 , including a third port connectable to the manually operable steering pump and a fourth port connectable to the hydraulic steering actuator, the control valve connecting the fourth port to the third port when said flow of fluid into the apparatus through the first port is detected, the control valve directing hydraulic fluid output from the powered hydraulic pump to the third port when a flow of fluid into the apparatus through the third port is detected, the first port being connected to the fourth port when said flow of fluid into the apparatus through the third port is detected, the controller operating the powered hydraulic pump when said flow of fluid into the apparatus through the third port is detected. 
     
     
       9. A hydraulic steering apparatus, comprising:
 a manually operable, hydraulic steering pump having a first steering pump port and a second steering pump port; 
 a steering actuator having a first steering actuator port and a second steering actuator port; 
 a powered hydraulic pump having a motor, an input port and an output port; 
 a directional control valve having a movable valve spool, a first valve port hydraulically connected to the first steering pump port, a second valve port hydraulically connected to the second steering pump port, a third valve port hydraulically connected to the first steering actuator port, a fourth valve port hydraulically connected to the second steering actuator port, a fifth valve port hydraulically connected to the input port of the powered hydraulic pump and a sixth valve port hydraulically connected to the output port of the powered hydraulic pump, the valve being hydraulically actuated, whereby hydraulic fluid flowing into the first valve port displaces the valve spool to connect to the first valve port to the fifth valve port, to connect the sixth valve port to the third valve port and to connect the fourth valve port to the second valve port; and hydraulic fluid flowing into the second valve port displaces the valve spool to connect the second valve port to the fifth valve port, to connect the sixth valve port to the fourth valve port and to connect the first valve port to the third valve port; p 1  a position sensor adjacent to the directional control valve for detecting position on the spool thereof; and 
 a motor controller operatively connected to the position sensor and to the motor for operating the motor, and thereby the powered hydraulic pump, when the spool of the direction control valve is displaced by hydraulic fluid flowing into the first valve port or the second valve port. 
 
     
     
       10. The apparatus as claimed in  claim 9 , wherein the controller is a proportional controller, whereby speed of the motor, and thereby speed of the powered hydraulic pump, is proportional to displacement of the spool of the directional control valve. 
     
     
       11. The apparatus as claimed in  claim 9 , wherein the powered hydraulic pump is connected hydraulically in series with the steering actuator and the manually operable, hydraulic steering pump. 
     
     
       12. The apparatus as claimed in  claim 11 , wherein the sensor includes a linear variable differential transformer. 
     
     
       13. The apparatus as claimed in  claim 11 , wherein the sensor is an anisotropic magnetoresistive sensor. 
     
     
       14. The apparatus as claimed in  claim 11 , wherein the sensor includes an integrated circuit with a plurality of anisotropic magnetoresistive sensors arranged in Wheatstone bridges. 
     
     
       15. The apparatus as claimed in  claim 11 , wherein the sensor is a Hall effect sensor. 
     
     
       16. The apparatus as claimed in  claim 11 , wherein the sensor is a giant magnetoresistive sensor. 
     
     
       17. A marine craft having a power assist steering system, comprising:
 a hull having a bow and a stern 
 a manually operable, hydraulic steering pump mounted in the hull and having a first steering pump port and a second steering pump port; 
 a steering actuator adjacent to the stern having a first steering actuator port and a second steering actuator port; 
 a powered hydraulic pump mounted in the hull having a motor, an input port and an output port; 
 a directional control valve having a movable valve spool, a first valve port hydraulically connected to the first steering pump port, a second valve port hydraulically connected to the second steering pump port, a third valve port hydraulically connected to the first steering actuator port, a fourth valve port hydraulically connected to the second steering actuator port, a fifth valve port hydraulically connected to the input port of the powered hydraulic pump and a sixth valve port hydraulically connected to the output port of the powered hydraulic pump, the valve being hydraulically actuated, whereby hydraulic fluid flowing into the first valve port displaces the valve spool to connect to the first valve port to the fifth valve port, to connect the sixth valve port to the third valve port and to connect the fourth valve port to the second valve port; and hydraulic fluid flowing into the second valve port displaces the valve spool to connect the second valve port to the fifth valve port, to connect the sixth valve port to the fourth valve port and to connect the first valve port to the third valve port; 
 a position sensor adjacent to the directional control valve for detecting position on the spool thereof; and 
 a motor controller operatively connected to the position sensor and to the motor for operating the motor, and thereby the powered hydraulic pump, when the spool of the direction control valve is displaced by hydraulic fluid flowing into the first valve port or the second valve port. 
 
     
     
       18. The craft as claimed in  claim 17 , wherein the controller is a proportional controller, whereby speed of the motor, and thereby speed of the powered hydraulic pump, is proportional to displacement of the spool of the directional control valve. 
     
     
       19. The craft as claimed in  claim 18 , wherein the powered hydraulic pump is connected hydraulically in series with the steering actuator and the manually operable, hydraulic steering pump. 
     
     
       20. The craft as claimed in  claim 19 , wherein the position sensor includes a sensor. 
     
     
       21. The craft as claimed in  claim 17 , wherein the sensor includes a linear variable differential transformer. 
     
     
       22. The craft as claimed in  claim 17 , wherein the sensor is an anisotropic magnetoresistive sensor. 
     
     
       23. The craft as claimed in  claim 17 , wherein the sensor includes an integrated circuit with a plurality of anisotropic magnetoresistive sensors arranged in Wheatstone bridges. 
     
     
       24. The craft as claimed in  claim 17 , wherein the sensor is a Hall effect sensor. 
     
     
       25. The craft as claimed in  claim 17 , wherein the sensor is a giant magnetoresistive sensor. 
     
     
       26. A method for providing power assisted steering for a marine craft having a manually operable steering pump and a hydraulic steering actuator, the method comprising:
 hydraulically connecting a powered hydraulic pump between the manually operable pump and the actuator, connecting to the manually operable pump and the powered hydraulic pump a control valve with a movable member, and placing adjacent to the control valve a sensor for sensing a position of the movable member, the member being displaced by hydraulic fluid entering the control valve, the sensor sensing said displacement of the member and operating the powered hydraulic pump to assist in pumping hydraulic fluid from the manually operable pump to the actuator. 
 
     
     
       27. A hydraulic steering apparatus, comprising:
 a manually operable, hydraulic steering pump; 
 a hydraulic steering actuator; 
 hydraulic conduits hydraulically connecting the manually operable pump to the actuator, whereby manual operation of the manually operable pump moves the actuator; 
 a powered hydraulic pump hydraulically connected by the conduits between the manually operable pump and the actuator; 
 means for operating the powered hydraulic pump when the manually operable pump is operated to assist movement of the hydraulic steering actuator, said means being actuated by sensing a volume of fluid displaced by the manually operable pump, said means for operating including a hydraulic cylinder hydraulically connected to the manually operable steering pump and a member sealingly and reciprocatingly received within the cylinder, whereby said member moves when the hydraulic cylinder receives hydraulic fluid from the manually operable steering pump, a position sensor adjacent to said member which senses a position of said member, and a controller coupled to the powered pump, the sensor being operatively connected to the controller and said sensor providing a signal to the controller to operate the powered hydraulic pump when the position of the member changes; and 
 means for providing a negative feedback, equivalent to output of the powered hydraulic pump, to the means for operating for maintaining said output of the powered hydraulic pump commensurate with said volume of fluid displaced by the manually operable pump. 
 
     
     
       28. The apparatus as claimed in  claim 27 , wherein the position sensor senses a control volume of fluid in the cylinder representing a volume of fluid outputted by the steering pump less fluid outputted from the cylinder to the powered pump. 
     
     
       29. A hydraulic steering apparatus, comprising:
 a manually operable, hydraulic steering pump; 
 a hydraulic steering actuator; 
 hydraulic conduits hydraulically connecting the manually operable pump to the actuator, whereby manual operation of the manually operable pump moves the actuator; 
 a powered hydraulic pump hydraulically connected by the conduits between the manually operable pump and the actuator; 
 means for operating the powered hydraulic pump when the manually operable pump is operated to assist movement of the hydraulic steering actuator, said means being actuated by sensing a volume of fluid displaced by the manually operable pump; and 
 an input flow sensor which senses output of the steering pump, a feedback flow sensor which senses output of the powered pump and a comparator which compares signals from the input flow sensor and the feedback flow sensor and provides a signal to the powered pump, whereby said output of the powered pump is regulated according to said output of the steering pump and accordingly of a desired steering position. 
 
     
     
       30. A method for providing power assisted steering for a marine craft having a manually operable steering pump and a hydraulic steering actuator, the method comprising:
 hydraulically connecting a powered hydraulic pump between the manually operable pump and the actuator, connecting to the manually operable pump and the powered hydraulic pump a control valve with a movable member, and placing adjacent to the control valve a sensor for sensing a position of the movable member, the member being displaced by hydraulic fluid entering the control valve, the sensor sensing said displacement of the member and operating the powered hydraulic pump through a controller to assist in pumping hydraulic fluid from the manually operable pump to the actuator, the controller being a proportional controller and the powered hydraulic pump being operated at a speed proportional to movement of the manually operable pump and to movement of the movable member.